Dont use deprecated Page() defaultNamespace param

Running script nowcommons causes the following deprecation notices to appear
twice on startup:
  WARNING: defaultNamespace argument of __init__ is deprecated; use ns instead.

Removing it from the nowcommons and blockreview scripts.

Change-Id: If8ca72d62f85577e306f4fe0be490632e69f805e
Merge "Dont use deprecated Page() defaultNamespace param"